<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<style>
		canvas{
			margin:100px auto;
			border:1px solid #ccc;
			display:block;
		}
	</style>
	<body>
		<canvas width="600" height="600">当前浏览器不支持</canvas>
		
	   <script>
		   var cas=document.querySelector("canvas")
		   // 2.获取上下文对象
		   var ctx=cas.getContext('2d')
		   var count=0
            var deg=Math.PI*2/360
		   var timer=setInterval(function(){
			   count++
			   ctx.beginPath()
			 //圆心定位 x  y 圆大小 
			   ctx.arc(250,250,200,0,count*deg,false)
			   ctx.strokeStyle="red"
			   // console.log(1)
			   ctx.lineWidth=10
			   ctx.stroke()
			   if(count==360){
				   clearInterval(timer)
			   }
		   },10)
		   
	   </script>
	
		
	</body>
</html>
			   ctx.arc(250,250,200,-Math.PI/2,11,false)
